1. Field of the Invention
The present invention relates to a technique for laying out a plurality of objects to overlap each other, and changing an overlap order of the objects.
2. Description of the Related Art
Conventionally, when the user creates a document, a slide for a presentation, or the like using an application program installed in a personal computer, he or she lays out objects such as an icon, graphic, and image to overlap each other.
When a plurality of objects are laid out to overlap each other, the user often interchanges overlap orders (Z-orders) of the objects.
For example, a UI used to instruct to interchange Z-orders of objects is displayed in response to a user operation, and the user changes the Z-order to attain the desired overlap orders using the UI. The UI displays, for example, four commands “Bring to front”, “Bring forward”, “Send backward”, and “Send to back”, and the user changes the overlap orders of objects by repeating selection from these commands.
Also, a method of selecting and moving one of objects having overlapping to temporarily cancel overlapping, and moving that object to an original position to overlap the other object, thereby interchanging the hierarchical relation between the selected object and the other object has been disclosed (see Japanese Patent Laid-Open No. 2007-328029).
However, with the aforementioned method of Japanese Patent Laid-Open No. 2007-328029, even when another object having overlapping with two objects exists between the two objects having overlapping, Z-orders are changed. For this reason, an overlap relation which is not intended by the user is obtained.
For example, a case will be examined below wherein objects A, B, and C are laid out to overlap each other so as to have Z-orders in an order of C, B, and A from the front surface, and object C directly overlap objects A and B, respectively, as shown in FIG. 12A. At this time, object C is moved to cancel overlapping between objects A and C, but overlapping between objects B and C is maintained, as shown in FIG. 12B. After that, when object C is moved to the position in FIG. 12A to overlap object A, Z-orders are changed. After the Z-orders are changed, according to Japanese Patent Laid-Open No. 2007-328029, object C is controlled to underlap object A, thus obtaining an overlap relation shown in FIG. 12C.
At this time, in the state of FIG. 12B, although overlapping between objects C and B is not canceled, Z-orders of these two objects are also changed. Hence, a physically unnatural order change, which is not intended by the user, is made. That is, a change in overlap relation of objects, which is not intuitive for the user, occurs.
Even when the user moves object C to the position in FIG. 12B, and then moves object C to the original position to restore the state shown in FIG. 12A, the method of Japanese Patent Laid-Open No. 2007-328029 requires troublesome operations since the state of FIG. 12C has to be temporarily required.